Printing surface



I March 11, 1930; ALLMAN 1,750,562-

PRINTING SURFACE Fil ed March 16, 1929 Fig.1. I

Fig.2.

Inventor P. flllmam .dttorney.

Patented Mar. 11, 1930 UNITED STATES YETER ALLMAN, OF MANCHESTER, ENGLAND PRINTING SURFACE Application filed March 16, 1929, Serial No. 347,708, and in Great Britain February 16, 1928.

This invention relates to printing surfaces produced in the form of thin flexible electrotyped or other sheets that in known manner are applied upon a support or cylin- 6 der and secured thereon, as, for example, by the engagement of the oppositely disposed longitudinal edges of the curved sheet within a gap or gaps in the cylinder.

The invention is illustrated diagrammati- 10 cally in the accompanying drawing, in which Figure 1 is a diagrammatic cross-section through a printing cylinder in which the contact faces of the printing cylinder which are to receive the printing surface, sheet or plate have applied thereon a layer or film of enamel; and

Figure 2 is a corresponding diagrammatic cross-section to Figure 1 in which a layer or film of enamel is applied upon the printing surface, sheet or plate.

The invention has among its objects to provide an elastic jointing or packing between the printing surface, sheet or plate and the cylinder that is not loose, and that while it is impervious to moisture and unafi'ected by ink, is adapted to provide an elastic seating for the printing surface, sheet or plate, by which a constant and uniform elastic resistance is imposed in impression.

According to the invention alternatively the contact faces of the printing cylinder a (Figure 1) which are to receive the printing surface, sheet or plate b have applied thereon a layer or film of enamel 0.

According to the invention the inner face of the printing surface, sheet or plate I) has applied thereon a layer or film of enamel 0.

The enamel may be applied with a brush or by spraying or by dipping, and may be 40 applied repeatedly and in a determined thickness of layer, and with a view to ensure precision in the thickness of the layer of pack ing thus applied, the surface of the packing may be ground to a uniform extent in the flat and before the sheet or plate is applied upon the cylinder.

Such an enamel may be made of a bitumen such as that which is marketed under the registered trade mark Gilsonite and a solvent 0 such as mineral naphtha. The bitumen is ground to a fine condition and admixed with the solvent into the uniform consistency of a thick paint, that may be applied by means of a brush or by spraying or otherwise. The sheet or plate or the printing cylinder with the layer of enamel thus applied may then be subjected to heat treatment within an oven at a temperature for example of 650 F. whereby the solvent is evaporated and the enamel may set as an integral part of the sheet or plate or cylinder.

The enamel may be applied repeatedly after drying of the layer first applied or its subjection to heat treatment whereby the desired thickness of layer is secured.

It will be understood that no limitation is involved to the use of the enamel specifically described.

According to the invention the enamel applied may be coloured so as thus to be used as an indicator of the colour of the plate in multi-colour printing. The use of the enamel as the colour indicator of a plate is calculated to be of special utility in carrying out intaglio printing processes more quickly, more simply and more reliably. In carrying this part of the invention into effect a solution of shellac in methylated spirit may be used and applied in the same manner as the bitumen and particular colouring pigments or dyes may be added in the solvent before application so that thus a particular colour is imparted to the shellac enamel applied that may correspond with the colour of the plate in its use in multi-colour printing.

I claim A printing plate, adapted for use on cylinders of printing presses, and a backing on said plate comprising a resilient layer of hardened bituminous composition closely adherent to the plate.

PETER ALLMAN. 

